This invention relates generally to neutral beam generators and more specifically to intensity controllers for neutral beam generators.
This invention is a result of a contract with the United States Department of Energy.
In the development of various fusion energy devices, such as the Mirror Fusion Test Facility (MFTF), a neutral particle beam is used as one source of heating the plasma. The neutral beam is transmitted to the device through a defining aperture (.about..+-.0.3.degree.) to the MFTF plasma. The neutral beam must be variable in intensity (particle current) over a range of at least 30% to 100% of full scale at a fixed energy.
In order to meet this requirement, some means of control is needed that is external of the neutral beamline ion source. The reason is that if the ion source is detuned at constant energy in order to vary the neutral beam intensity, it impairs the source reliability, lowers the full energy species yield, and puts an intolerably high power loading on ion source grids and on beamline aperature plates. With the detuning method the throttled beam of neutral particles would not have the same energy spectrum as when operated under full power conditions.